1. Technical Field
The present invention relates to a radio communication base station apparatus, radio communication terminal apparatus and channel assignment method.
2. Description of the Related Art
In 3GPP-LTE, an OFDMA (Orthogonal Frequency Division Multiple Access) is adopted as a downlink communication scheme. In a radio communication scheme adopting 3GPP LTE, a radio communication base station apparatus (hereinafter simply “base station”) transmits a synchronization channel (“SCH”) and broadcast channel (“BCH”) using predetermined communication resources. Then, first, a radio communication terminal apparatus (hereinafter simply “terminal”) secures synchronization with the base station by capturing the SCH. After that, the terminal obtains parameters unique to the base station (such as a frequency bandwidth) by reading BCH information (see Non-Patent Literatures 1, 2 and 3).
Also, in 3GPP LTE, HARQ (Hybrid Automatic Repeat reQuest) is applied to uplink data transmitted from the terminal to the base station in uplink. In HARQ, the base station performs CRC (Cyclic Redundancy Check) detection of uplink data and feeds back an ACK (Acknowledgement) if CRC=OK (no error) or a NACK if CRC=NG (error present), to a mobile station as a response signal. These response signals are transmitted via a physical channel for downlink response signal transmission such as PHICH (Physical Hybrid-ARQ Indicator Channel).
Also, standardization of 3GPP LTE-advanced, which realizes faster communication than 3GPP LTE, has been started (see Non-Patent Literature 4). The 3GPP LTE-advanced system (hereinafter “LTE+ system”) follows the 3GPP LTE system (hereinafter “LTE system”).